diff --git a/foamlib/_files/_files.py b/foamlib/_files/_files.py
index 95b5daf..1c80cd7 100644
--- a/foamlib/_files/_files.py
+++ b/foamlib/_files/_files.py
@@ -472,3 +472,7 @@ def boundary_field(self) -> "FoamFieldFile.BoundariesSubDict":
             assert not isinstance(ret, FoamFile.SubDict)
             raise TypeError("boundaryField is not a dictionary")
         return ret
+
+    @boundary_field.setter
+    def boundary_field(self, value: Mapping[str, FoamFile._Dict]) -> None:
+        self["boundaryField"] = value